Redundant array of independent NAND for a three-dimensional memory array

ABSTRACT

The present disclosure includes a redundant array of independent NAND for a three dimensional memory array. A number of embodiments include a three-dimensional array of memory cells, wherein the array includes a plurality of pages of memory cells, a number of the plurality of pages include a parity portion of a redundant array of independent NAND (RAIN) stripe, and the parity portion of the RAIN stripe in each respective page comprises only a portion of that respective page.

PRIORITY INFORMATION

This application is a Continuation of U.S. application Ser. No.15/053,719 filed Feb. 25, 2016, the contents of which are includedherein by reference.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory andmethods, and more particularly, to a redundant array of independent NANDfor a three-dimensional memory array.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits and/or external removable devices in computers orother electronic devices. There are many different types of memoryincluding volatile and non-volatile memory. Volatile memory can requirepower to maintain its data and can include random-access memory (RAM),dynamic random access memory (DRAM), and synchronous dynamic randomaccess memory (SDRAM), among others. Non-volatile memory can retainstored data when not powered and can include NAND flash memory, NORflash memory, phase change random access memory (PCRAM), resistiverandom access memory (RRAM), and magnetic random access memory (MRAM),among others.

Memory devices can be combined together to form a solid state drive(SSD). An SSD can include non-volatile memory (e.g., NAND flash memoryand/or NOR flash memory), and/or can include volatile memory (e.g., DRAMand/or SRAM), among various other types of non-volatile and volatilememory. An SSD can be used to replace hard disk drives as the mainstorage volume for a computer, as the solid state drive can haveadvantages over hard drives in terms of performance, size, weight,ruggedness, operating temperature range, and power consumption. Forexample, SSDs can have superior performance when compared to magneticdisk drives due to their lack of moving parts, which may avoid seektime, latency, and other electro-mechanical delays associated withmagnetic disk drives. SSD manufacturers can use non-volatile flashmemory to create flash SSDs that may not use an internal battery supply,thus allowing the drive to be more versatile and compact.

Flash memory devices, such as those used to create flash SSDs, caninclude memory cells storing data in a charge storage structure such asa floating gate, for instance, and may be utilized as non-volatilememory for a wide range of electronic applications. Flash memory devicestypically use a one-transistor memory cell that allows for high memorydensities, high reliability, and low power consumption.

Memory cells in an array architecture can be programmed to a target(e.g., desired) state. For instance, electric charge can be placed on orremoved from the charge storage structure (e.g., floating gate) of amemory cell to program the cell to a particular data state. The storedcharge on the charge storage structure of the memory cell can indicate athreshold voltage (Vt) of the cell, and the state of the cell can bedetermined by sensing the stored charge (e.g., the Vt) of the cell.

For example, a single level cell (SLC) can be programmed to a targetedone of two different data states, which can be represented by the binaryunits 1 or 0. Some flash memory cells can be programmed to a targetedone of more than two data states (e.g., 1111, 0111, 0011, 1011, 1001,0001, 0101, 1101, 1100, 0100, 0000, 1000, 1010, 0010, 0110, and 1110).Such cells may be referred to as multi state memory cells, multiunitcells, or multilevel cells (MLCs). MLCs can provide higher densitymemories without increasing the number of memory cells since each cellcan represent more than one digit (e.g., more than one bit).

During operation of a flash memory device, a number of defects and/orerrors, such as, for instance, electrical shorts between differentcomponents of the memory, may occur. Such defects and/or errors cancause data stored in the memory to be lost, which can result in afailure of the memory. One approach to protect against such a memoryfailure (e.g., to protect the data stored in the memory) is to use aredundant array of independent NAND (RAIN) data protection scheme, whichcan divide and/or replicate the data stored in the memory among multiplememory devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a portion of athree-dimensional memory array in accordance with a number ofembodiments of the present disclosure.

FIG. 2 is a schematic diagram illustrating connection between a portionof a three-dimensional memory array and a string driver in accordancewith a number of embodiments of the present disclosure.

FIG. 3 illustrates an example of a three-dimensional memory array inaccordance with a number of embodiments of the present disclosure.

FIG. 4 is a chart illustrating an example of data storage in athree-dimensional memory array in accordance with a number ofembodiments of the present disclosure.

FIG. 5 is a functional block diagram of a computing system including anapparatus in the form of a memory device in accordance with a number ofembodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure includes a redundant array of independent NANDfor a three-dimensional memory array. A number of embodiments include athree-dimensional array of memory cells, wherein the array includes aplurality of pages of memory cells, a number of the plurality of pagesinclude a parity portion of a redundant array of independent NAND (RAIN)stripe, and the parity portion of the RAIN stripe in each respectivepage comprises only a portion of that respective page.

The amount of protection provided by a RAIN protection scheme may dependon the overhead density (e.g., the footprint) of the RAIN in the memory.For example, the amount of data in a memory that can be protected by aRAIN protection scheme may depend on the size of (e.g., number of memorycells in) the portion of the memory dedicated to the RAIN. For instance,the greater the size of the RAIN-dedicated portion of the memory, thegreater the amount of protection that may be provided by the RAINagainst failure of the memory. However, as the size of theRAIN-dedicated portion of the memory increases, the amount of the memoryavailable to store other data, such as user data, decreases.

RAIN protection approaches in accordance with the present disclosure,however, can have a lower overhead density than previous RAIN protectionapproaches, while providing the same (or similar) amount of protectionas previous RAIN protection approaches. For example, the size of theRAIN-dedicated portion in a three-dimensional memory array in accordancewith the present disclosure can be one-fourth the size of a RAINdedicated portion in previous RAIN protection approaches, whileproviding the same (or similar) amount of protection, thereby allowingthe memory to store a greater amount of user data than previousapproaches.

As used herein, “a number of” something can refer to one or more suchthings. For example, a number of memory cells can refer to one or morememory cells. Additionally, the designator “N”, as used herein,particularly with respect to reference numerals in the drawings,indicates that a number of the particular feature so designated can beincluded with a number of embodiments of the present disclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 100 may referenceelement “00” in FIG. 1, and a similar element may be referenced as 200in FIG. 2.

FIG. 1 illustrates a perspective view of a portion of athree-dimensional memory array 100 in accordance with a number ofembodiments of the present disclosure. The memory array 100 cancomprise, for example, a NAND flash memory array. Memory array 100includes a number of vertical strings of series-coupled memory cells 103oriented orthogonal to a number of conductive lines, such as accesslines 105 and/or data lines 102. In the example illustrated in FIG. 1,memory cells 103 can form a group of memory cells, such as, forinstance, a tile group. That is, the portion of memory array 100illustrated in FIG. 1 can correspond to a group (e.g., tile group) ofmemory cells.

As used herein, A “coupled to” B refers to A and B being operativelycoupled together, such as where A and B are electrically connected witheach other, such as through a direct ohmic connection or through anindirect connection. Insulating materials between various conductivelines are omitted from FIG. 1 for clarity. Conductive materials can beformed of polysilicon, for example, or other doped or undoped materials.Insulating materials can be formed of oxide, for example, or otherdielectric materials.

A plurality of data lines 102 can be oriented in a first plane, andfurther oriented in a first direction in the first plane, the verticalstrings of series-coupled memory cells 103 being oriented orthogonal tothe first plane. A plurality of access lines 105 can be oriented in asecond plane, and further oriented in a second direction in the secondplane. As shown in FIG. 1, the access lines 105 can be formed in aplanar configuration. The second plane can be substantially parallel tothe first plane. The second direction can be perpendicular to the firstdirection, for example. The data lines 102 can be shared by a number ofvertical strings of series-coupled memory cells 103 in the firstdirection, and the access lines 105 can be shared by a number ofvertical strings of series-coupled memory cells 103 in the seconddirection.

One or more source lines 104 can be oriented in a third plane, the thirdplane being substantially parallel to the first and second planes. Thesource lines 104 can be further oriented in the second direction, forinstance, the same direction as the access lines 105 as shown in FIG. 1,or in a different direction. The select gates 108 and 110 can operate toselect a particular vertical string of series-coupled memory cells 103between a data line 102 and a source line 104. As such, the verticalstrings of series-coupled memory devices 103 can be located at theintersections of the data lines 102 and source line 104.

The access lines 105 are coupled to (and in some cases form) controlgates of memory cells at a particular level and can be used to select aparticular one of the series-coupled memory cells within a verticalstring. In this manner, a particular memory cell can be selected andelectrically coupled to a data line 102 via operation of the firstselect gate 108, second select gate 110, and an access line 105. Theaccess lines 105 can be configured to select a memory cell at aparticular location within one or more of the vertical strings ofseries-coupled memory cells 103.

As illustrated in FIG. 1, the planar access lines 105 can be configuredto have multiple three-dimensional stair step structures 106 tofacilitate vertically-oriented coupling thereto, such as by verticalconductors 112. As such, respective planar access lines 105 can beformed as respective stair steps of the stair step structure 106. Astair step structure 106, as used herein, means a three-dimensionalstructure having a plurality of stair steps at different elevationsextending to different distances in a lateral direction, such as isgenerally associated with a set of stair steps. According to oneembodiment of the present disclosure, the steps of lower elevations canextend laterally beyond the lateral distance that the step at animmediately higher elevation extends, as shown in FIG. 1. For instance,lower steps extend further in a lateral direction than step(s) above. Alower step can extend laterally a sufficient distance beyond a nexthigher step so that a vertical coupling can be made to the portion ofthe lower step extending laterally past the next higher step. In thismanner, a vertical conductor 112 can be coupled to the lower step, suchas to an access line 105, select gate 108 or 110, or source line 104,which each can correspond to a step in the stair step structure 106.

The memory array 100 can be coupled to various circuitry associated withoperating the memory array 100. Such circuitry can include string drivercircuitry, for instance, as will be described further in connection withFIG. 2. As an example, horizontal conductive lines 114 can be routedfrom the memory array 100, for example, to a string driver. Steps of thestair step structure 106 can be coupled to the conductive lines 114, forinstance, via the vertical conductors 112. In this manner, an electricalcoupling can be made between the vertical stack of access lines 105,select gates 108/110, and/or source lines 104, and the string driver,via the planar horizontal conductive lines 114.

The strings of NAND memory cells can be arranged with select gatetransistors coupled at each end (e.g., source, drain). Each string caninclude a number of memory cells coupled in series, drain-to-source.Vertical strings of NAND memory cells can be arranged such that thestring of series-coupled memory cells are linearly arranged in avertical orientation, or can be arranged in non-linear configurationsuch as in a “U” shape, with portions of the “U” shape being orientedvertically, for example. For instance, the string of series-coupledmemory cells can be arranged in a dimension orthogonal to the planesencompassing the access lines (e.g., word lines) and data lines (e.g.,bit lines).

FIG. 2 is a schematic diagram illustrating connection between a portionof a three-dimensional memory array 200 and a string driver 216 inaccordance with a number of embodiments of the present disclosure.Memory array 200 can be, for example, memory array 100 previouslydescribed in connection with FIG. 1.

String driver 216 can be used to control selection of particular stringsof memory cells and/or particular memory cells, such as by applicationof a voltage signal of particular select gates and/or particular memorycells within the strings of memory cells by, for instance, appropriateassertion of access lines 206. FIG. 2 illustrates the access lines 206,select gate 208 (SGD), and select gate 210 (SGS) of memory array 200being coupled to a string driver 216 via a number of conductive lines214. Conductive lines 214, and/or the area between memory array 200 andstring driver 216 in which conductive lines 214 couple memory array 200to string driver 216, can be referred to as an interface between memoryarray 200 and string driver 216. The string driver 216 can be formedusing CMOS devices, for example. The memory array 200 further includesthe data lines 202 arranged as shown and coupled to the strings ofmemory cells.

The access lines 206, select gate 208 (SGD), and select gate 210 (SGS)of a memory array 200 can be coupled to respective global access lines228 through selection transistors 218. The selection transistors 218 canbe field effect transistors (FETs), for example. The selectiontransistors 218 can be controlled via the block high voltage switchoutput (BLKHVSW_OUT) signal line 226, which is coupled between an outputof a block high voltage switch 220 and, for example, the gate of each ofthe selection transistors 218. The block high voltage switch 220receives as inputs, for example, a block selection address 222 and aninput voltage 224 to produce the BLKHVSW_OUT signal on the block highvoltage switch output signal line 226 when appropriate to couple theaccess lines 206, select gate 208 (SGD), and select gate 210 (SGS) ofmemory array 200 to the global access lines 228.

In a sense operation, such as a read or a program verify operation,global access line driver 216 can provide positive voltage signals toglobal access lines 228 (e.g., global word lines) to select a particularlocal access line coupled to memory cells being sensed. Unselectedaccess lines, such as access lines not coupled to memory cells beingread or verified, can be provided with a pass voltage (Vpass), while theselected access line can be provided with a read voltage. Othertechniques are possible for reading and/or programming memory cells, aswill be appreciated by one of skill in the art. According to variousembodiments, the memory array 200 can be implemented as athree-dimensional memory array with the strings being orientedvertically, and the string driver 216, including the selectiontransistors 218, can be implemented as a substantially planar device. Astair step structure comprising the conductive lines 214 can be used toelectrically couple the vertical three-dimensional array and horizontalplanar structures (e.g., string driver 216).

FIG. 3 illustrates an example of a three-dimensional memory array 330 inaccordance with a number of embodiments of the present disclosure. Asshown in FIG. 3, memory array 330 can include a plurality of portions300-0, 300-1, 300-2, and 300-3. Each respective portion 300-0, 300-1,300-2, and 300-3 of memory array 330 can be analogous to the portion ofmemory array 100 previously described in connection with FIG. 1. Forexample, memory array 330 can be a three-dimensional NAND flash memoryarray comprising portions 300-0, 300-1, 300-2, and 300-3 having a stairstep structure, as previously described in connection with FIG. 1.Further, each respective portion 300-0, 300-1, 300-2, 300-3 cancorrespond to a group (e.g., a tile group) of memory cells, aspreviously described in connection with FIG. 1. Although the embodimentillustrated in FIG. 3 includes four portions (e.g., four groups ofmemory cells), embodiments of the present disclosure are not so limited.

Although not shown in FIG. 3 for clarity and so as not to obscureembodiments of the present disclosure, each respective portion (e.g.,group) 300-0, 300-1, 300-2, and 300-3 of memory array 330 can have astring driver analogous to string driver 216 previously described inconnection with FIG. 2 associated therewith. For example, eachrespective group 300-0, 300-1, 300-2, and 300-3 can have a differentstring driver coupled to and configured to operate that respectivegroup, in a manner analogous to that described in connection with FIG.2. Further, the string drivers can operate their respective groups inparallel. For example, the string drivers can perform program and/orsense operations on their respective groups in parallel.

Memory array 330 can include a number of physical blocks of memorycells, such as, for instance, 128 blocks, 512 blocks, or 1,024 blocks.However, embodiments are not limited to a particular multiple of 128 orany particular number of physical blocks. A number of physical blocks ofmemory cells can be included in a plane of memory cells, and a number ofplanes of memory cells can be included on a die. Each physical block ofmemory cells can include a number of physical rows of memory cellscoupled to access lines (e.g., word lines), and each row can include anumber of pages of memory cells (e.g., physical pages). A physical pagerefers to a unit of programming and/or sensing (e.g., a number of memorycells that are programmed and/or sensed together as a functional group).For example, each row can comprise one physical page of memory cells, oreach row can comprise multiple physical pages of memory cells (e.g., oneor more even pages of memory cells coupled to even-numbered bit lines,and one or more odd pages of memory cells coupled to odd numbered bitlines). Additionally, for embodiments including multilevel cells, aphysical page of memory cells can store multiple pages (e.g., logicalpages) of data (e.g., an upper page of data and a lower page of data,with each cell in a physical page storing one or more bits towards anupper page of data and one or more bits towards a lower page of data).

In a number of embodiments, each respective group 300-0, 300-1, 300-2,and 300-3 of memory array 330 can include a different portion of eachrespective page of memory cells. For instance, group 300-0 can include afirst portion of each respective page, group 300-1 can include a secondportion of each respective page, etc. As such, memory array 330 caninclude a plurality of groups of memory cells (e.g., tile groups 300-0,300-1, 300-2, and 300-3) and a plurality of pages of memory cells,wherein each respective group includes a different portion of eachrespective page.

A number of the pages of memory cells in memory array 330 can include(e.g., store) a parity portion of a redundant array of independent NAND(RAIN) stripe. For instance, each respective one of the number of pagescan include a parity portion of a different RAIN stripe. RAIN, as usedherein, is an umbrella term for computer information (e.g., data)storage schemes that divide and/or replicate (e.g., mirror) informationamong multiple pages of multiple memory devices, for instance, in orderto help protect the data stored in the memory devices. The multiplememory devices in a RAIN array may appear to a user and the operatingsystem of a computer as a single memory device (e.g., disk). RAIN caninclude striping (e.g., splitting) information so that differentportions of the information are stored on different pages of differentmemory devices. The portions of the more than one device that store thesplit data are collectively referred to as a stripe. In contrast, RAINcan also include mirroring, which can include storing duplicate copiesof data on more than one page of more than one device. As an example ofthe former, write data can be striped across N−1 of N memory devices,where error information can be stored in an Nth memory device.

A RAIN stripe can include (e.g., be a combination of) user data andparity data. The parity data of the RAIN stripe, which can be referredto herein as the parity portion of the RAIN stripe, can include errorprotection data that can be used to protect user data stored in thememory against defects and/or errors that may occur during operation ofthe memory. For example, the RAIN stripe (e.g., the parity portion ofthe RAIN stripe) stored in memory array 330 can protect user data storedin memory array 330 against defects and/or errors that may occur duringoperation of the memory, and can therefore provide protection against afailure of the memory. Defects and/or errors the RAIN stripe can provideprotection against include electrical shorts that may occur betweendifferent components of the memory, such as, for example, access line toaccess line shorts that may occur in groups 300-0, 300-1, 300-2, and/or300-3 and/or shorts that may occur at the interface between groups300-0, 300-1, 300-2, and/or 300-3 and the respective string driverassociated therewith, as will be further described herein.

In a number of embodiments, the parity portion of the RAIN stripe storedin each respective page can comprise only a portion of that page. Thatis, the parity portion of the RAIN stripe stored in each respective pagemay comprise less than all of that page. For instance, the parityportion of the RAIN stripe stored in each respective page may compriseone-fourth of that respective page. As such, the size of the parityportion of each respective RAIN stripe can be less than the size of thepage in which the parity portion of that RAIN stripe is stored. Forinstance, only one-fourth of the cells of the page may be used to storethe parity portion of the RAIN stripe. However, embodiments of thepresent disclosure are not limited to this example. For instance, theparity portion of the RAIN stripe stored in each respective page maycomprise more or less than one-fourth of that respective page. Further,the size of the parity portion of each respective RAIN stripe cancorrespond to (e.g., be the same size as) the size of each differentportion of each respective page included in each respective group ofmemory cells. The parity portion of each respective RAIN stripe can bestored in the same group of memory cells, or different parity portionsof different RAIN stripes can be stored in different groups.

The remaining portion of each respective page of memory cells thatincludes a parity portion of the RAIN stripe, as well as the pages thatdo not include any portion of the RAIN stripe, can include (e.g., store)user data. For example, if the parity portion of the RAIN stripe storedin a page comprises one-fourth of that page, then three-fourths of thatpage can be used to store user data. In such an example, the portion ofeach respective page that includes the parity portion of the RAIN stripecan be a portion of one of the groups of memory cells (e.g., group300-1, 300-2, 300-3, or 300-4), and the remaining portion of thatrespective page that includes user data can be portions of the othergroups of memory cells. An example further illustrating the storage theRAIN stripe and user data in memory array 330 will be further describedherein (e.g., in connection with FIG. 4).

In contrast, in previous RAIN protection approaches, the parity portionof the RAIN stripe that would be stored in each respective page ofmemory cells would comprise the entire page. That is, in previous RAINprotection approaches, the parity portion of the RAIN stripe that wouldbe stored in each respective page would comprise all of that page. Assuch, in previous approaches, each respective page of memory cells thatincludes a parity portion of the RAIN stripe would not also be able toinclude, or be used to store, user data, thereby reducing the amount ofmemory that would be available to store user data as compared toembodiments of the present disclosure. For instance, the size of theparity portion of the RAIN stripe in previous RAIN protection approachesmay be four times the size of the parity portion of the RAIN stripe inembodiments of the present disclosure. In such an example, four times asmany memory cells may be needed to store the parity portion of the RAINstripe than in embodiments of the present disclosure.

However, even though the RAIN stripe (e.g., the parity portion of theRAIN stripe) of the present disclosure uses less overhead than the RAINstripe in previous approaches, the RAIN stripe of the present disclosuremay still provide the same (or similar) amount of protection as the RAINstripe in previous approaches. For example, the RAIN stripe of thepresent disclosure can provide protection for each group 300-0, 300-1,300-2, and 300-3 of memory array 330. For instance, the RAIN stripe ofthe present disclosure can provide protection for all user data storedin each group 300-0, 300-1, 300-2, and 300-3 of memory array 330.

The RAIN stripe of the present disclosure can provide the same (orsimilar) amount of protection as the RAIN stripe in previous approachesbecause, for example, of the tile group structure of memory array 330.For instance, because memory array 330 includes (e.g., is broken into)groups 300-0, 300-1, 300-2, and 300-3, with each respective group havinga three-dimensional stair step structure and its own respective stringdriver coupled thereto, any defects and/or errors that may result in afailure of memory array 330, such as, for instance, access line toaccess line shorts and/or string driver interface shorts, are likely tooccur in only one of the groups. Because the probability of such defectsand/or errors occurring in more than one of the groups is so much lessthan the probability of such defects and/or errors occurring in only oneof the groups, the RAIN stripe of the present disclosure may only haveto provide protection against a failure that may occur in only one groupto be able to effectively provide protection for all groups.

FIG. 4 is a chart 440 illustrating an example of data storage in athree-dimensional memory array in accordance with a number ofembodiments of the present disclosure. The three dimensional memoryarray can be, for example, memory array 330 having tile groups 300-0,300-1, 300-2, and 300-3, and the data stored therein can include RAINstripes having user data and parity data (e.g., a parity portion), aspreviously described herein (e.g., in connection with FIG. 3). In theexample illustrated in FIG. 4, tile groups 300-0, 300-1, 300-2, and300-3 are represented as tg0, tg1, tg2, and tg3, respectively.

In the example illustrated in FIG. 4, the memory array includes threelogical units (represented as LUN0, LUN1, and LUN2), and each respectivelogical unit includes four planes of memory cells (plane0, plane1,plane2, and plane3). Further, the memory array includes two blocks ofmemory cells (represented as Blk0 and Blk1), and each respective blockincludes nine pages of memory cells (represented as page0, page 1, . . .page8). As an example, page 442-0 illustrated in FIG. 4 is page 0 ofblock 0 of plane 0 of LUN 0, and the memory cells of page 442-0 storeuser data, as represented by the four R0 s, with each different R0representing a different portion of the user data of a first RAIN stripe(e.g., RAIN stripe 444-0). Further, page 442-1 is page 1 of block 0 ofplane 0 of LUN 0, and the memory cells of page 442-1 store user data, asrepresented by the four R1 s, with each different R1 representing adifferent portion of the user data of a second RAIN stripe (e.g., RAINstripe 444-1), and so on, up to page 442-8, which is page 8 of block 0of plane 0 of LUN 0, and whose memory cells store user data, asrepresented by the four R8 s, with each different R8 representing adifferent portion of the user data of a ninth RAIN stripe (e.g., RAINstripe 444-8).

In the example illustrated in FIG. 4, each respective page of memorycells can store 16 kB of data. For instance, each respective R0 of page442-0 represents 4 different kB of user data, such that 16 kB of userdata is stored in page 442-0. However, embodiments of the presentdisclosure are not limited to these data amounts.

Further, each respective group of the memory array can include adifferent portion of each respective page of memory cells. For instance,in the example illustrated in FIG. 4, each page of memory cells includesfour different portions, with each different portion a part of adifferent one of the four groups. As an example, group tg0 includes afirst portion of page 442-0, group tg1 includes a second portion of page442-0, group tg2 includes a third portion of page 442-0, and group tg3includes a fourth portion of page 442-0, with each portion including 4kB of data. For instance, user data R0 in the tg0 column of page 442-0illustrated in FIG. 4 is stored in the memory cells of page 0 of block 0that are in group tg0, user data R0 in the tg1 column of page 442-0 isstored in the memory cells of page 0 of block 0 that are in group tg1,user data R0 in the tg2 column of page 442-0 is stored in the memorycells of page 0 of block 0 that are in group tg2, and user data R0 inthe tg3 column of page 442-0 is stored in the memory cells of page 0 ofblock 0 that are in group tg3.

As shown in FIG. 4, a RAIN stripe can be stored across different pagesof memory cells in the memory array, with a different portion of theRAIN stripe stored in each respective page. For instance, the exampleillustrated in FIG. 4 includes nine RAIN stripes, with each RAIN stripestored across different pages of memory cells. As an example, RAINstripe 444-0 includes each different portion R0 of user data stored ineach respective page 0 of each respective block of each respective planeof each respective LUN, as well as parity portion P0 stored in page 0 ofblock 1 of plane 3 of LUN 2. Further, RAIN stripe 444-1 includes eachdifferent portion R1 of user data stored in each respective page 1 ofeach respective block of each respective plane of each respective LUN,as well as parity portion P1 stored in page 1 of block 1 of plane 3 ofLUN 2, and so on, up to RAIN stripe 444-8, which includes each differentportion R8 of user data stored in each respective page 8 of eachrespective block of each respective plane of each respective LUN, andparity portion P8 stored in page 8 of block 1 of plane 3 of LUN 2. Assuch, the user data of a RAIN stripe comprises 95/96 of the stripe, andthe parity portion comprises 1/96 of the stripe. The parity portion ofeach respective RAIN stripe (e.g., parity portions P0 to P8) illustratedin FIG. 4 can protect the user data stored in the rest of the memoryarray against defects and/or errors that may occur during operation ofthe memory, as previously described herein.

Further, in the pages in which the parity portion of each respectiveRAIN stripe is stored, the parity portion comprises only a portion(e.g., less than all) of that page, as illustrated in FIG. 4. Forinstance, in the example illustrated in FIG. 4, the parity portion ofeach respective RAIN stripe comprises one-fourth of the page in which itis stored. That is, the parity portion of RAIN stripe 444-0 (e.g., P0)comprises one-fourth of page 0 of block 1 of plane 3 of LUN 2, theparity portion of RAIN stripe 444-1 (e.g., P1) comprises one-fourth ofpage 1 of block 1 of plane 3 of LUN 2, parity portion P2 comprisesone-fourth of page 2 of block 1 of plane 3 of LUN 2, etc. As such, thesize of the parity portion of each respective RAIN stripe is less thanthe size of the page in which it is stored. For instance, one-fourth ofthe memory cells of page 0 of block 1 of plane 3 of LUN 2 are used tostore parity portion P0, one-fourth of the memory cells of page 1 ofblock 1 of plane 3 of LUN 2 are used to store parity portion P1,one-fourth of the memory cells of page 2 of block 1 of plane 3 of LUN 2are used to store parity portion P2, etc. Further, in the exampleillustrated in FIG. 4, each different parity portion P0 to P8 is storedin the same group of memory cells (e.g., group tg3).

As shown in FIG. 4, user data is stored in the remaining portions ofeach respective page of memory cells in which a parity portion of one ofthe RAIN stripes is stored, as well as in the pages of the memory arrayin which no parity portions of the RAIN stripes is stored. For example,three-fourths of the memory cells of page 0 of block 1 of plane 3 of LUN2 are used to store user data, three-fourths of the memory cells of page1 of block 1 of plane 3 of LUN 2 are used to store user data,three-fourths of the memory cells of page 2 of block 1 of plane 3 of LUN2 are used to store user data, etc. Further, the portion of eachrespective page in which a parity portion of one of the RAIN stripes isstored can be a portion of one of the groups of memory cells, and theremaining portions of that respective page that include user data can beportions of the other groups of memory cells. For example, parityportion P0 of RAIN stripe 444-0 is a portion of group tg3, while theremaining portions of page 0 of block 1 of plane 3 of LUN 2 that includeuser data are portions of groups tg0, tg1, and tg2, as illustrated inFIG. 4.

FIG. 5 is a functional block diagram of a computing system 550 includingan apparatus in the form of a memory device 554 in accordance with anumber of embodiments of the present disclosure. As used herein, an“apparatus” can refer to, but is not limited to, any of a variety ofstructures or combinations of structures, such as a circuit orcircuitry, a die or dice, a module or modules, a device or devices, or asystem or systems, for example.

Memory device 554 can be, for example, a solid state drive (SSD). In theembodiment illustrated in FIG. 5, memory device 204 includes a physicalhost interface 556, a number of memories 560-1, 560-2, . . . , 560-N,and a controller 558 coupled to physical host interface 556 and memories560-1, 560-2, . . . , 560-N. Controller 558 can be, for example, an SSDcontroller, and memories 560-1, 560-2, . . . , 560-N can be, forexample, solid state memory devices.

Memories 560-1, 560-2, . . . , 560-N can include, for example, a numberof non-volatile memory arrays (e.g., arrays of non-volatile memorycells). For instance, memories 560-1, 560-2, . . . , 560-N can include anumber of memory arrays analogous to three-dimensional memory array 330previously described in connection with FIG. 3.

Physical host interface 556 can be used to communicate informationbetween memory device 554 and another device such as a host 552. Host552 can include a memory access device, such as a processor. One ofordinary skill in the art will appreciate that “a processor” can intenda number of processors, such as a parallel processing system, a numberof coprocessors, etc. Example hosts can include personal laptopcomputers, desktop computers, digital cameras, digital recording andplayback devices, mobile phones such as, for instance, smart phones,PDAs, memory card readers, interface hubs, and the like.

Physical host interface 556 can be in the form of a standardizedphysical interface. For example, when memory device 554 is used forinformation storage in computing system 550, physical host interface 556can be a serial advanced technology attachment (SATA) physicalinterface, a peripheral component interconnect express (PCIe) physicalinterface, or a universal serial bus (USB) physical interface, amongother physical connectors and/or interfaces. In general, however,physical host interface 556 can provide an interface for passingcontrol, address, information (e.g., data), and other signals betweenmemory device 554 and host 552 having compatible receptors for physicalhost interface 556.

Controller 558 can include, for example, control circuitry and/or logic(e.g., hardware and firmware). Controller 558 can be included on thesame physical device (e.g., the same die) as memories 560-1, 560-2, . .. , 560-N. For example, controller 558 can be an application specificintegrated circuit (ASIC) coupled to a printed circuit board includingphysical host interface 556 and memories 560-1, 560-2, . . . , 560-N.Alternatively, controller 558 can be included on a separate physicaldevice that is communicatively coupled to the physical device thatincludes memories 560-1, 560-2, . . . , 560-N. In a number ofembodiments, components of controller 558 can be spread across multiplephysical devices (e.g., some components on the same die as the memory,and some components on a different die, module, or board) as adistributed controller.

Controller 558 can communicate with memories 560-1, 560-2, . . . , 560-Nto sense (e.g., read), program (e.g., write), and/or erase information,among other operations. Controller 558 can have circuitry that may be anumber of integrated circuits and/or discrete components. For example,controller 558 can include RAIN component 562, as illustrated in FIG. 5.RAIN component 562 can include XOR circuitry, and can be configured tocalculate error information (e.g., parity data), including programmingand/or sensing data in stripes across memories 560-1, 560-2, . . . ,560-N.

For instance, RAIN component 562 can program data to a RAIN stripe inmemories 560-1, 560-2, . . . , 560-N, such as, for instance, the RAINstripe of memory array 330 and/or RAIN stripes 444-0, 444-1, . . . ,444-8 previously described herein in connection with FIGS. 3 and 4,respectively. Further, RAIN component 562 can sense the data stored inthe RAIN stripe(s). The programming and sensing of the RAIN stripe(s)can be performed as tile-based operations, in accordance with the tilegroup stair step structure of the memories previously described herein.

As an example, RAIN component 562 can detect that a failure has occurredin one of the tile groups of memories 560-1, 560-2, . . . , 560-N. Thefailure may occur due to, for instance, access line to access lineshorts and/or string driver interface shorts, as previously describedherein. Upon detecting the failure, RAIN component can sense the datastored in the RAIN stripe(s), and recover the data stored in the memory,including the data stored in the tile group in which the failureoccurred, using the sensed data from the RAIN stripe(s).

The embodiment illustrated in FIG. 5 can include additional circuitry,logic, and/or components not illustrated so as not to obscureembodiments of the present disclosure. For example, memory device 554can include address circuitry to latch address signals provided over I/Oconnectors through I/O circuitry. Address signals can be received anddecoded by a row decoders and column decoders, to access memories 560-1,560-2, . . . , 560-N.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of a number of embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of ordinary skill in the artupon reviewing the above description. The scope of a number ofembodiments of the present disclosure includes other applications inwhich the above structures and methods are used. Therefore, the scope ofa number of embodiments of the present disclosure should be determinedwith reference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, some features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

What is claimed is:
 1. An apparatus, comprising: a three-dimensionalarray of memory cells, wherein: the array includes a plurality of pagesof memory cells and a plurality of groups of memory cells, wherein eachrespective group includes a different portion of each respective pageand each respective group has a three-dimensional stair step structure;and a number of the plurality of pages include a parity portion of aredundant array of independent NAND (RAIN) stripe; a controllerconfigured to perform programming and sensing of the RAIN stripe astile-based operations in accordance with the three-dimensional stairstep structure of the groups of memory cells; and a plurality of stringdrivers, wherein each respective string driver is associated with adifferent one of the groups of memory cells having the three-dimensionalstair step structure.
 2. The apparatus of claim 1, wherein the parityportion of the RAIN stripe in each respective page comprises only aportion of that respective page.
 3. The apparatus of claim 1, whereineach respective one of the number of pages includes a parity portion ofa different RAIN stripe.
 4. The apparatus of claim 1, wherein theplurality of pages of memory cells comprise a plurality of physicalpages of memory cells.
 5. The apparatus of claim 1, wherein thethree-dimensional stair step structure of each respective group ofmemory cells comprises a plurality of stair steps, wherein eachrespective stair step is formed by a different planar access line of thethree-dimensional array at a different elevation of the array.
 6. Theapparatus of claim 5, wherein each respective stair step extends to adifferent distance in a lateral direction of the three-dimensionalmemory array.
 7. The apparatus of claim 5, wherein each respective stairstep is coupled to a different planar horizontal conductive line of thethree-dimensional array via a different vertical conductor of the array.8. The apparatus of claim 7, wherein each respective string driver iscoupled to the group of memory cells with which that string driver isassociated via the planar horizontal conductive lines coupled to therespective stair steps of that group.
 9. A method of operating memory,comprising: storing a parity portion of a redundant array of independentNAND (RAIN) stripe in a portion of a number of pages of memory cells ina plurality of groups of memory cells in a three-dimensional array ofmemory cells, wherein each respective group includes a different portionof each respective page and each respective group has athree-dimensional stair step structure; performing programming andsensing of the RAIN stripe as tile-based operations in accordance withthe three-dimensional stair step structure of the groups of memorycells; and controlling selection of the memory cells using a pluralityof string drivers, wherein each respective string driver is associatedwith a different one of the groups of memory cells having thethree-dimensional stair step structure.
 10. The method of claim 9,wherein the method includes storing user data in an additional portionof the number of pages of memory cells.
 11. The method of claim 9,wherein the method includes controlling the selection of the memorycells by using the plurality of string drivers to apply a voltage signalto the memory cells being selected.
 12. The method of claim 11, whereinthe plurality of string drivers apply the voltage signal to the memorycells being selected by applying the voltage signal to planar accesslines of the three-dimensional array to which the memory cells beingselected are coupled.
 13. The method of claim 9, wherein the methodincludes controlling the selection of the memory cells using theplurality of string drivers during a sense operation being performed onthe three-dimensional array.
 14. The method of claim 9, wherein themethod includes controlling the selection of the memory cells using theplurality of string drivers during a program operation being performedon the three-dimensional array.
 15. An apparatus, comprising: athree-dimensional array of memory cells, wherein: the array includes aplurality of groups of memory cells and a plurality of pages of memorycells, wherein each respective group includes a different portion ofeach respective page and each respective group has a three-dimensionalstair step structure; and a number of the plurality of pages include aparity portion of a redundant array of independent NAND (RAIN) stripe; acontroller configured to perform programming and sensing of the RAINstripe as tile-based operations in accordance with the three-dimensionalstair step structure of the groups of memory cells; and a plurality ofstring drivers configured to control selection of the memory cells,wherein each respective string driver is associated with a different oneof the groups of memory cells having the three-dimensional stair stepstructure.
 16. The apparatus of claim 15, wherein the parity portion ofthe RAIN stripe is included in a single page of memory cells.
 17. Theapparatus of claim 15, wherein the parity portion of the RAIN stripe ineach respective page is stored in less than all of that page.
 18. Theapparatus of claim 15, wherein each respective string driver includes aplurality of selection transistors configured to control the selectionof the memory cells of the group with which that string driver isassociated.
 19. The apparatus of claim 18, wherein the apparatusincludes a switch configured to control the selection transistors ofeach respective string driver.
 20. The apparatus of claim 15, whereineach respective string driver is substantially planar with thethree-dimensional stair step structure of the group with which thatstring driver is associated.